Regarding the suspension, in what part of SoCal are you? Unless you've played around with the suspension and still aren't satisfied, I'd work with what you have before I spent money on it, and I'd probably rework the shock before the fork.
As to the engine, the thing that tweaks my view of your question is that it's '14. Ordinarily, I would totally agree with Monk that if there's nothing wrong with a leak down test you should just check the valve clearance and leave it alone. It's wise to replace the timing chain on an annual basis or thereabouts, just as a preventative measure, but the engine isn't know for needing very much attention in the first 100 hours.
The '14 was the first year of the 4th generation YZ450. The Gen4 is basically a Gen3 with a wet sump lube system and a change in the way the shift forks work. Lots of other things were worked over in the upgrade, such as some head work, etc., and one of those changes was the connecting rod. Follow that tidbit with the fact that Yamaha abruptly replaced the '14 rod (1SL-11651-00-00) with a redesigned unit (33D-11651-03-00). Tidbit #3 is that there have been a small number of reports of small end rod failure in '14 models. That is, such reports have been made of '14's, but NOT any significant reports involving any other model year.
Now, it would still be an assumption to conclude that the '14 rod is dangerously flawed to the point that they should all be replaced to avoid eminent doom, but it would be enough for me to consider an early tear down for whatever mods I might want to make and replace the rod in the process. Piston? Maybe, depending on what the skirts and ring grooves looked like. On the one hand, it probably won't need one, but replacing it would add another 75 hours to the time 'til the next piston.
The only actual facts I have on the "problem" with the rod are that the small end breaks open (as opposed to breaking off), and that there had been some unusual noise from the engine that wasn't one of the normal bunch of noises YZF's have always been known for, and that Yamaha felt like it needed more than a little rework. Not much to go on.